This invention relates generally to a cutting tool for use in a rotary power tool. More particularly, the invention relates to a rotary cutter head for releasably holding cutting blades formed with cutting edges which extend radially outwardly of and generally axially along the outer periphery of the cutter head. Cutter heads of this general type are typically used in power machines such as routers, edgebanders, or tenoners and are typically used to chamfer, round, or otherwise shape an edge portion of a workpiece of either ferrous or non-ferrous material.
In general, a cutter head of this type is formed with at least one recess for receiving a cutting blade. The recess extends generally radially inwardly from the outer periphery of the cutter head and extends substantially axially in the cutter head. Frequently, the recess extends across the entire width of the cutter head.
Prior cutter heads of this general type utilize threaded fasteners and a so-called gib to releasably secure the blade in the recess. The gib is shaped to generally conform to the shape of the recess and is sized to allow the gib and the blade to be slidably received in the recess. When installing a blade into the cutter head, the gib and the blade are manually located in the recess. The threaded fasteners are then screwed into threaded openings formed in the cutter head to draw the gib toward one side of the recess so as to wedge or otherwise clamp the blade in the recess. The blade and the gib used in these cutter heads must be manually aligned relative to one another and relative to the recess when they are installed into the recess. Moreover, this alignment must then be maintained until the gib and the blade are secured in the recess.
In one prior cutter head, the fasteners extend through openings formed in the gib, and the heads of the fasteners engaging the gib to secure the gib and the blade in the recess. In this instance, each time that the blade is changed, the gib and the fasteners must be removed from and reinstalled into the recess.
In another prior cutter head, the fasteners draw pins through openings formed in the gib. The pins are formed with enlarged heads which engage the gib and which wedge the gib and the blade in the recess. In this case, the gib and the pins need not be removed from the recess to change the blade. However, the gib and the blade must still be manually aligned as the fasteners are tightened. Moreover, the pins and the gib used in this cutter head easily fall out of the recess when the fasteners are inadvertently loosened too far.
The gib used in some prior cutter heads is formed with a fixed locating pin for establishing relative alignment between the gib and the blade. In such a cutter head, the locating pin is received into an opening formed in the blade before the gib and the blade are placed into the recess. While the fixed locating pin aids in establishing and maintaining alignment between the gib and the blade, the gib and the fasteners must be removed and reinstalled each time the blade is changed. Moreover, the gib and the blade must still be aligned relative to the recess.
In addition to a gib and the associated fasteners and pins, prior cutter heads are typically equipped with a back-up fastener to prevent the blade from flying out of the cutter head in the event that the gib loosens while the cutter head is rotating or in the event that the fasteners which secure the gib are not tightened before the machine is turned on. The back-up fastener extends through an opening in the blade and must either be backed out or completely removed from the cutter head before the blade can be removed from the recess. The back-up fastener must then either be turned inwardly or reinstalled when a new blade is installed in the cutter head.
In summary, while prior cutter heads utilize numerous arrangements to secure a cutting blade into a recess, each of these arrangements can lead to substantial downtime of a machine due to the time required to change the blades when the cutting edges of the blades become dull from use.